Stem cells help after vision loss

Two legally blind women appeared to gain some vision after receiving an experimental treatment using embryonic stem cells, scientists reported Monday. Researchers cautioned that the work is still very preliminary.

"This study provides reason for encouragement, but plans to now get such a treatment would be premature," said stem cell expert Paul Knoepfler of the University of California at Davis, who had no role in the research.

Last summer, each patient was injected in one eye with cells derived from embryonic stem cells at the University of California at Los Angeles. One patient had the "dry" form of age-related macular degeneration, the most common cause of blindness. The other had a rare disorder known as Stargardt disease that causes serious vision loss. There's no cure for either eye problem.

After four months, both showed some improvement in reading progressively smaller letters on an eye chart.

Both patients remain legally blind despite their improvements, said experts not connected with the study.

The findings were published online Monday by the journal Lancet. The test was meant to study whether the stem cell therapy was safe in people and not whether it would improve vision.